Terracotta Army's vibrant make-up was made of ox glue

The 8000 strong warriors of the Terracotta Army in Xi’an, China, are a formidable enough sight today – but imagine if you could see the whites of their eyes and the blood in their cheeks. When the army was buried 2000 years ago the life-size figurines were painted in a variety of bright hues, including green, blue, pink, red, black, white and lilac. Only traces of that colour remain now, after looting, fire, centuries of water damage and exposure to the open air – all of which took their toll on the paint.

Now we know how these vibrant pigments adhered to the brown clay – animal glue made from ox parts. A team from Northwest University and the Museum of Emperor Qin Shihuang’s Terracotta Army, Xi’an, made the match by comparing the protein molecules in the original paint with artificially aged model samples daubed with different types of binding media.

Now that the paint’s components are better understood, researchers can develop ways to conserve what paint is left, particularly on the thousands of soldiers that still remain to be unearthed.